Gas-dispersing means for plate columns

ABSTRACT

In a plate column including a plurality of spaced horizontal plates provided with downcomers, a plurality of openings in the plates for passage of the vapors upwardly, and short nipples disposed in the openings, the improvement residing in the provision over the nipples of rotatable, vertically movable disks having circumferentially arranged fan elements. The diameter of the disks is such that when insufficient quantity of vapor is generated, the disks descend onto the short nipples to block flow of any vapor therethrough. A fan wheel may be provided below each disk in the vapor space of the lower plate to restrict escape of entrained liquid particles.

United States Patent Heckmann et a].

[ 1 Aug. 22, 1972 [54] GAS-DISPERSING MEANS FOR PLATE COLUMNS [72]Inventors: Carl-Justus Heckmann, Stieglitzstr. 67; Michael l-leckmann,Holbeinstr. 1, both of 7031 Leipzig, Germany [73] Assignee: HeckmannwerkK G, Leipzig, Germany [22] Filed: Feb. 18, 1969 [21.] Appl. No.: 800,219

[52] US. Cl...- ..26l/ll4 R, 261/114 VT [51] Int. Cl. ..B0ld 3/16 [58].Field ofSearch.26l/1l4,114.1,114 VT, 114 JP [56] References CitedUNITED STATES PATENTS 973,795 10/1910 Lummus ..261/l14.1 2,893,7137/1959 l-laltmeier ..261/114.1 3,055,646 9/1962 Eld et a1. ..26l/114 VT3,143,582 8/1964 Jones et a1 ..261/1 14 VT 3,025,041 3/1962 Sandler..261/114 VT FOREIGN PATENTS OR APPLICATIONS 721,247 l/l955 GreatBritain..26l/l14.1 1,286,882 11/1962 France... ..261/ll4VT Primary Examiner-TimR. Miles Assistant Examiner--Steven H. Markowitz Att0meyl-lammond &Littell ABSTRACT In a plate column including a plurality of spacedhorizontal plates provided with downcomers, a plurality of openings inthe plates for passage of the vapors upwardly, and short nipplesdisposed in the openings, the improvement residing in the provision overthe nipples of rotatable, vertically movable disks havingcircumferentially arranged fan elements. The diameter of the disks issuch that when insufficient quantity of vapor is generated, the disksdescend onto the short nipples to block flow of any vapor therethrough.A fan wheel may be provided below each disk in the vapor space of thelower plate to restrict escape of entrained liquid particles.

3 Claim, 5 Drawing Figures PATENTED M1622 1912 F IG .1?

FIG .5

INVENE CARL-JUSTUS H MAN IMICHAE L HE CKMAN MN. nu

ATTORNEYS GAS-DISPERSIN G MEANS FOR PLATE COLUMNS PRIOR ART The knownfractionating plate columns which are utilized for liquid-gas contactingmay be divided into two classifications:

l. cross-flow plate, and

2. counter-flow plate.

The cross-flow tray requires a liquid downcomer and .is more generallyused than counter-flow tray because of transferefficiency advantages andgreater operating range. The flow pattern of the liquid on a cross-flowtray can be controlled by varying the placement of downcomers in orderto increase stability of operation or improve mass-transfer efficiency.

Where the liquid loading on a column is less than 60-80 gal./min-ft. ofweir, a normal cross-flow pattern with segmental outlet weir isgenerally used. In the event the liquid loading exceeds 60-80gal./min.-ft. of weir, in a column having sufficient vapor capacity,split-flow and sometimes radial flow are used.

The fraction of column cross-sectional area available for gas-dispersioncomponents, such as caps or perforations, is significantly lower insplit-flow design than in cross-flow design. Thus, for the same vaporcapacity, split-flow design generally requires a larger column diameterthan normal cross-flow.

Elements used in plate towers for the purpose of gas dispersion arebubble caps, sieve perforations, or modifications thereof.

The tray construction, wherein the liquid is maintained on the traysurface by the kinetic energy of the vapor, is called the sieve tray.The openings in the tray may take the form of circles or slits formed bymechanical punching of the metal tray.

A more effective method of insuring contact between the vapor and thereflux of a fractionating column is the use of bubble caps on the trays.Each plate in the column has a plurality of openings and each of theopenings is provided with a short nipple. Each nipple is surmounted witha bell-shaped cap which is secured in place by means of a spider and abolt. The lower edge of the cap may be serrated or provided with slots.As the vapor rises through a nipple from the plate below, it is diverteddownward by the cap and bubbles out under the serrations or through theslots. A layer of liquid is maintained on the plate and the depth of theliquid is such that the caps are submerged. The downpipe from the plateabove is sealed by liquid on the plate below, so that vapor cannot enterthe downpipe. Ordinarily, the liquid is delivered at one end of the trayby a downpipe from the plate above, flows across the tray, and isdischarged by a downpipe onto the lower tray. Baffles can be placedbetween the caps to divert the liquid and cause uniform flow across thetray.

The shortcomings of the known trays are severalfold: the constructioncosts are high; there is a considerable loss in pressure as the vaportraverses from the boiler to the top of the column; and the undesirabletransfer of entrained liquid particles through the openings in the traysto the liquid on that tray detrimentally interferes with theconcentration differential of the liquid and the vapor.

2 i OBJECTS OF THE INVENTION It is an object of this invention toprovide an improved gas-dispersing assembly.

It is another object to provide a simple device which can bemanufactured at a reduced cost.

It is another object to provide a device which would reduce the escapeof entrained liquid to the upper trays.

It is still another object to provide a gas-dispersing assembly havingagreater mass-transfer efficiency between liquid and vapor.

THE INVENTION shaft in response to the vapor passing through the nipple.A fan wheel is disposed on the same shaft in the vapor space of thelower plate below the disk for the purpose of reducing the carry-over ofentrained liquid from a lower tray to an upper tray in a column.

DESCRIPTION OF THE DRAWINGS In the appended drawings,

FIG. 1 is a cross+sectional view of a plate column, partially insection.

FIG. 2 is a side view of the novel tray.

FIG. 3 is a plan view of the novel tray.

FIG. 4 is a view, partially in section, through the tray, showing thenovel gas-dispersion components.

FIG. 5 is a plan view of the gas-dispersion disk.

DESCRIPTION OF THE INVENTION Referring to the drawings, a plurality oftrays 2 are disposed along the length of distillation or fractionationcolumn 1. These trays are provided with gas-dispersing assemblies 3which are effective in providing a more efficient contacting of theliquid phase with the vapor phase. I

The liquid phase enters column 1 through inlet 4, traverses tray 2 andgas-dispersing assemblies 3 in cross-flow fashion, flows to the nextlower tray 2 via downcomer, and so on to the outlet 5. The vapor phaseis fed to inlet 6, passes upwardly through the gasdispersing assemblies3, thus coming in contact and being dispersed in liquid phaseflowingdownwardly, and leaves the column through outlet 7.

Details of the gas-dispersing assembly are illustrated in FIG. 4. Tray 2supports a flowing stream of a liquid phase. The level of the stream isindicated by 16. An opening 8 is provided in tray 2. A short nipple or apiece of pipe 9 is disposed in the opening 8 and extends vertically toan elevation below liquid phase level 16. Bearing 12 is secured to thebottom of tray 2 concentrically with the nipple 9. Shaft 10 is joumaledin the bearing 12 supporting disk 11 at one end and a fan wheel 14 atthe other. Shaft is journaled loosely in the bearing 12 to permit freerotation and vertical movement of disk 11 and fan wheel 14. Arrows l8denote swirling of liquid phase on tray 2 in the vicinity of thegas-dispersing assembly 3 as it moves across to the downcomer. Arrows 17show the direction of deformed to provide spaces 15.

The function of the gas-dispersing assembly 3, shown in FIG. 4, is tobeing the gas or vapor phase into intimate contact with the liquid phaseto thus effect a mass transfer of light components from the liquid phaseto vapor phase and the heavier components from the vapor phase to theliquid phase. When no vapor is generated in column 1, or wheninsufficient vapor is generated, disk 1 l rests on short nipple 9. Thediameter I of disk 11 is such that it completely covers short nipple 9thus obstructing any flow of the vapor from the. lower tray to the uppertray. The diameter of disk 11 can be somewhat smaller than the insidediameter of short nipple 9 to permit some flow of vapor'to the uppertray when the disk is resting on the nipple. When sufficientvapor hasbeen generated, and thereby sufficient pressure has been built up, thedisk is lifted above the short nipple and the vapor enters through thenipple and is dispersed in the liquid phase, as shown by arrows 17. Asis evident from FIG. 4, at least some of the vapor flows through spacesand is thereby more efficiently dispersed, resulting in a highermass-transfer efficiency.

Disk 11 and fan wheel 14 can be either loosely or rigidly mounted onshaft 10. It ispreferred to mount them loosely to permit each to rotateon shaft 10 independently of each other. In this manner, rotation ofdisk 11 will be controlled by the currents in the liquid phase, whilerotation of fan wheel 14 will be dictated by I spaces 15 on the disk.Vapor from the lower tray flows through and around these spaces. Fanwheel 14 is pro vided for the purpose of reducing the carry over ofentrained liquid particles to the upper tray since such carry over has adetrimental effect on the concentration balance of the components in theliquid and vapor form drops of liquid which fall to the tray below.

Various modifications of the gas-dispersing assembly described above maybe made without departing from t 't th d t t d t Jl t tilin vrifigfl'isufiflmilledoli s fe .llefifn t e appended claims.

We claim:

1. ma liquid-gas contact plate column comprising a plurality ofvertically spacedhorizontal trays for retaining a body of descendingliquid thereon, a plurality of uniformly spaced openings in said traysfor allowing an ascending vapor phase to pass therethrough, a shortcylindricalconduit disposed concentrically in association with each ofsaid openings and extending above said tray to a height below the levelof liquid on said tray, and vapor pressure-responsive self-adjustingvalve means in association with each of said cylindrical conduits, saidvalvemean including a shaft disposed concentrically within said conduitand projecting from I both ends thereof and freely-mounted for rotationand axial. movement in said conduit, the improvement which consists of adisk mounted on said shaft above. said tray, the diameter of aid diskbeing at least as great I as the inside'diameter of .said' conduit, fanelements disposed on the periphery of said disk with spacestherebetween, the 'diametrical extent of said fan elements being atleast as great as the outside diameter of said conduit, a fan wheelmounted on said shaft portion extending below said tray, and aperturesin said fan wheel.

2. In a liquid-gas contact plate column according to claim 1, said fanwheel comprising fan elements arranged circumferentially thereon andspacesbetween said fan elements.

3. In a liquid-gas contact plate column according to claim 1, said diskand said fan wheel being rotatably mounted on said shaft.

1. In a liquid-gas contact plate means comprising a plurality ofvertically spaced horizontal trays for retaining a body of descendingliquid thereon, a plurality of uniformly spaced openings in said traysfor allowing an ascending vapor phase to pass therethrough, a shortcylindrical conduit disposed concentrically in association with each ofsaid openings and extending above said tray to a height below the levelof liquid on said tray, and vapor pressure-responsive self-adjustingvalve means in association with each of said cylindrical conduits, saidvalve mean including a shaft disposed concentrically within said conduitand projecting from both ends thereof and freely mounted for rotationand axial movement in said conduit, the improvement which consists of adisk mounted on said shaft above said tray, the diameter of aid diskbeing at least as great as the inside diameter of said conduit, fanelements disposed on the periphery of said disk with spacestherebetween, the diametrical extent of said fan elements being at leastas Great as the outside diameter of said conduit, a fan wheel mounted onsaid shaft portion extending below said tray, and apertures in said fanwheel.
 2. In a liquid-gas contact plate column according to claim 1,said fan wheel comprising fan elements arranged circumferentiallythereon and spaces between said fan elements.
 3. In a liquid-gas contactplate column according to claim 1, said disk and said fan wheel beingrotatably mounted on said shaft.